Reaction of 2-thiouracil with carboxylic acid 1,2,2,2-tetrachloroethylamides

Amidoalkylation of 2-thiouracil with 1,2,2,2-tetrachloroethylamides in the presence of triethylamine or sodium hydroxide gives products of S-, O-, and N-substitution, depending on the reaction conditions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 95–100, January, 1992.     

Luminescence of Eu<Superscript>2+</Superscript> ions in alkaline earth dilithiosilicates

Spectral-luminescent properties of Eu²⁺ ions in alkaline earth dilithiosilicates of composition MLi₂SiO₄ (M = Ca, Sr, Ba) have been studied at 77 K. The reasons for the different positions of the Eu²⁺ 4f ⁶5 d → 4f ⁷ emission band maximum in spectra of MLi₂SiO₄ were found based on the obtained results. It was shown that the increase in the decay time of the Eu²⁺ emission on going from CaLi₂SiO₄ (0.41μs) through BaLi₂SiO₄ (0.64 μs) to Sr-silicate (1.11μs) correlates with the shift of the emission maximum to longer wavelengths.     

Electrodynamic modeling of the spatial structure of electromagnetic fields in H-waveguides

We propose a method for electrodynamic computer-aided modeling and visualization of the structure of electromagnetic fields of H- and E-waves in an H-waveguide. The eigenvalues and eigenfunctions of the H-waveguide were determined using the method of partial regions allowing for the electromagnetic field singularity at the edge. The length of the electromagnetic field line was used as an independent parameter in the modeling. Rostov State University, Rostov-on-Don, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 8, pp. 1021–1031, August, 1998.     

Spiropyrans and spirooxazines. 1. Synthesis and photochromic properties of 9"-hydroxy- and 9"-alkoxy-substituted spironaphthooxazines

A procedure was developed for phase-transfer catalyzed alkylation of 5-hydroxyindolenine and 9"-hydroxy-substituted spiro[indoline-2,3"-naphtho[2,1-b]oxazines] by alkyl halides. New 9"-hydroxy- and 9"-alkoxy-substituted spironaphthooxazines, spirooxazinyloxyacetic acids, and their esters containing substituents with different length of the carbon chain in the indoline moiety were synthesized. The influence of the substituents on the spectroscopic properties of the starting and colored forms and the kinetic characteristics of photochromic transformations of 9"-substituted spironaphthooxazines in solutions and polymeric films was investigated. The bipolar merocyanine forms of spirooxazines were found to produce H-aggregates.     

Gas-chromatographic determination of formic acid in the oxidation products of organic substances

Procedures for the gas-chromatographic determination of formic acid in oxidation produts of organic substances after its conversion to benzyl formate were developed. In determining formic acid in an organic phase, free formic acid was esterified with benzyl alcohol in a pyridine solution while adding acetic anhydride under mild conditions. The conversion of formic acid was complete even in the presence of other mono-and dicarboxylic acids in considerable amounts. It was found that the formation of benzyl formate occurred via a mixed aldehyde formed in situ from formic acid and acetic anhydride. The determination of formic acid in aqueous solutions involves the synthesis of its sodium or potassium salt and the successive treatment of this salt with acetyl chloride and benzyl alcohol in a pyridine solution.